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Your search keyword '"Lee, Byeong‐ha"' showing total 656 results
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656 results on '"Lee, Byeong‐ha"'

1. All-optical in vivo photoacoustic tomography by adaptive multilayer temporal backpropagation

Author

Yoon, Taeil, Ko, Hakseok, Im, Jeongmyo, Chung, Euiheon, Choi, Wonshik, and Lee, Byeong Ha

Subjects
Physics - Optics
Abstract

Photoacoustic tomography (PAT) offers high optical contrast with acoustic imaging depth, making it essential for biomedical applications. While many all-optical systems have been developed to address limitations of ultrasound transducers, such as limited spatial sampling and optical path obstructions, measuring surface displacements on rough and dynamic tissues remains challenging. Existing methods often lack sensitivity for in vivo imaging or are complex and time-consuming. Here, we present an all-optical PAT system that enables fast, high-resolution volumetric imaging in live tissues. Using full-field holographic microscopy combined with a soft cover layer and coherent averaging, the system maps surface displacements over a 10 mm*10 mm area with 0.5 nm sensitivity in 1 second. A temporal backpropagation algorithm reconstructs 3D images from a single pressure map, allowing rapid, depth-selective imaging. With adaptive multilayer backpropagation, the system achieves imaging depths of up to 5 mm, with lateral and axial resolutions of 158 micrometer and 92 micrometer as demonstrated through in vivo imaging of mouse vasculature.

Published
2024

13. Ultrawideband photonic crystal fiber coupler for multiband optical imaging system.

Author

Ryu, Seon Young, Choi, Hae Young, Choi, Eun Seo, Tomov, Ivan, Chen, Zhongping, and Lee, Byeong Ha

Subjects
Physical Sciences, Engineering, Nanotechnology, Crystallization, Humans, Lasers, Optical Fibers, Tomography, Optical Coherence, Tooth, Optical Physics, Electrical and Electronic Engineering, Mechanical Engineering, Optics, Electrical engineering, Atomic, molecular and optical physics
Abstract

We report a photonic crystal fiber (PCF) coupler having an ultrawide spectral bandwidth keeping single mode operation. The use of the PCF coupler in a fiber-based optical coherence tomography (OCT) system enables us to handle the wide spectral bands of various light sources, including superluminescent diodes (SLDs) at 1300 nm and 820 nm, Ti:sapphire lasers, and white-light sources. The multiband imaging performances of the PCF-based OCT system are demonstrated by obtaining dental images at 1300 nm and 820 nm with the same setup. In addition, we show that the PCF coupler could cover the spectrum over a one octave span and guide both the fundamental wave (1030 nm) and the second harmonic wave (515 nm) simultaneously.

Published
2010

22. Comparative analysis of BZR1/BES1 family transcription factors in Arabidopsis.

Author

Kim, So‐Hee, Lee, Se‐Hwa, Park, Tae‐Ki, Tian, Yanchen, Yu, Kyoungjae, Lee, Byeong‐ha, Bai, Ming‐Yi, Cho, Sung‐Jin, and Kim, Tae‐Wuk

Subjects
TRANSCRIPTION factors, GENE regulatory networks, ARABIDOPSIS, GENETIC transcription regulation, COMPARATIVE studies
Abstract

SUMMARY: Brassinazole Resistant 1 (BZR1) and bri1 EMS Suppressor 1 (BES1) are key transcription factors that mediate brassinosteroid (BR)‐responsive gene expression in Arabidopsis. The BZR1/BES1 family is composed of BZR1, BES1, and four BES1/BZR1 homologs (BEH1–BEH4). However, little is known about whether BEHs are regulated by BR signaling in the same way as BZR1 and BES1. We comparatively analyzed the functional characteristics of six BZR1/BES1 family members and their regulatory mechanisms in BR signaling using genetic and biochemical analyses. We also compared their subcellular localizations regulated by the phosphorylation status, interaction with GSK3‐like kinases, and heterodimeric combination. We found that all BZR1/BES1 family members restored the phenotypic defects of bri1‐5 by their overexpression. Unexpectedly, BEH2‐overexpressing plants showed the most distinct phenotype with enhanced BR responses. RNA‐Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR‐responsive gene expression, but BEH2 has a much greater proportion of BR‐independent gene expression than BZR1. Unlike BZR1 and BES1, the BR‐regulated subcellular translocation of the four BEHs was not tightly correlated with their phosphorylation status. Notably, BEH1 and BEH2 are predominantly localized in the nucleus, which induces the nuclear accumulation of other BZR1/BES1 family proteins through heterodimerization. Altogether, our comparative analyses suggest that BEH1 and BEH2 play an important role in the functional interaction between BZR1/BES1 family transcription factors. Significance Statement: Our study is of significance as it thoroughly analyzed the functional characteristics of all six BZR1/BES1 family members and their regulatory mechanisms, which has not been attempted before. Our study expands the knowledge of the molecular mechanisms underlying the BR‐mediated transcriptional regulation network. [ABSTRACT FROM AUTHOR]

Published
2024
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48. Self-referenced spectral interferometry for simultaneous measurements of thickness and refractive index

Author

Na, Jihoon, Choi, Hae Young, Choi, Eun Seo, Lee, ChangSu, and Lee, Byeong Ha

Subjects
Refractive index -- Measurement, Thickness measurement -- Methods, Interferometry -- Methods, Fibers -- Properties, Fibers -- Usage, Astronomy, Physics
Abstract

We present a method for simultaneously measuring the thickness and the group refractive index of a specimen using self-referenced spectral-domain fiber-based interferometry. By removing the scanning part and using the fiber-based configuration, the system complexity and stability could be significantly improved. To minimize the system drift, we utilized the signals originated from the fiber ends of both arms. Implementing in a self-referenced configuration, we could improve the measurement accuracy down to a decimal place. Experimental measurements were made with a 1.555 mm thick fused silica plate. At 814 nm the thickness was measured as 1.5546 [+ or -] 0.0002 mm, and at the same time, the group index was obtained as 1.4627 [+ or -] 0.0002. OCIS codes: 120.3180, 120.4290, 170.4500.

Published
2009

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